You should wait before handling them. Wait until they are well acclimated and even then Uros aren't meant for handling. But I do know some people who do handle them and their Uros seem to calm down quite a lot. I guess it's up to you.

As for lentils. I serve it whole to my baby Uro, but you can grind it up in the coffee grinder if you like. I think the lentils are small enough for them to handle IMO.

Good luck with your URos!